Various compositions are known to be useful as treating agents to provide surface effects to substrates. Surface effects include repellency to moisture, soil and stain resistance, and other effects which are particularly useful for fibrous substrates such as fibers, fabrics, textiles, carpets, paper, leather and other such substrates. Many such treating agents are fluorinated polymers or copolymers.
Fluorinated polymer compositions having utility as fibrous substrate treating agents generally contain pendant perfluoroalkyl groups of three or more carbon atoms, which provide oil- and water-repellency when the compositions are applied to fibrous substrate surfaces. The perfluoroalkyl groups are generally attached by various connecting groups to polymerizable groups not containing fluorine. The resulting monomer is then generally copolymerized with other monomers which confer additional favorable properties to the substrates. Various specialized monomers may be incorporated to impart improved cross-linking, latex stability and substantivity. Since each ingredient may impart some potentially undesirable properties in addition to its desirable ones, the specific combination is directed to the desired use. These polymers are generally marketed as aqueous emulsions for easy application to the fibrous substrates.
Various attempts have been made to increase the oil- and water-repellency imparted to the substrate and its durability while reducing the amount of fluorinated polymer required, i.e., boost the efficiency or performance of the treating agent. One method is to incorporate blocked isocyanates or melamine resins. However, only limited amounts can be used because these ingredients tend to adversely affect the handle (the feel) of the fibrous substrate. Another method is the use of various extender polymers. These are typically hydrocarbon polymers in aqueous emulsions, which are blended with the fluorinated polymer emulsion before application to the substrate.
U.S. Pat. No. 3,657,173 discloses an emulsion suitable for imparting oil and/or water-repellency to substrates, containing a fluorinated polymer and a major amount of a halogenated solvent, a minor amount of an alkanol, and water. Optionally the emulsion may also contain a non-fluorine containing polymer, (i.e., an extender polymer), of at least one monovinyl compound free of non-vinylic fluorine atoms, or a non-fluorinated conjugated diene. Examples of the extender polymer are 2-hydroxy ethyl- or 2-hydroxy propyl-acrylate or methacrylate; and n-lauryl methacrylate or 2-ethylhexyl methacrylate. It is also said to be advantageous to include in all these polymers a small amount of units derived from N-methylolacrylamide or N-methylolmethacrylamide and glycidyl acrylate or methacrylate to improve durability of the polymer solids to laundering or dry-cleaning.
There is a need for polymer compositions which significantly improve the performance of surface effect agents. In particular, there is a need for compositions which improve the durability of surface effects for substrates while reducing the amount of fluorinated polymer required. The present invention provides such a composition.